Investigations on the scattering of light in colloidal solutions and gels. Part I—Agar sol and gel

One of the fundamental problems in the field of colloids is the investigation of their structure. This is a subject of considerable importance and has been attracting a great deal of attention from workers in this field. A systematic study of the various physical properties of colloids is essential for a clear understanding of the nature of the colloidal state. The optical properties are of special importance as they have the great advantage of revealing the structure of colloidal systems without disturbing their internal equilibrium. They furnish direct information concerning the size and the shape of the colloidal particles. In a series of papers, of which this is the first, the author proposes to publish investigations on the scattering of light in colloidal solutions and gels. An attempt will be made to discuss the various problems concerning their structure, as revealed by the study of the Tyndall effect in such systems.